Internal combustion engines burn fossil fuels such as petrol, diesel, kerosene, natural gas etc., and generate energy, which is used for transportation, pumping of liquids and for generating electricity. Fossil fuels are basically hydrocarbons, which contain predominantly carbon and hydrogen atoms. Burning of these fuels in internal combustion engines produces energy depending on efficiency of the engine, and a large quantity of un-burnt/partially burned fuel and other pollutants. 70% of air pollution in urban areas is due to burning of fossil fuels in internal combustion engines. Some of these pollutants are harmful and some are harmless. Harmful pollutants are CO, NOx, SOx, hydrocarbons, and volatile organic compounds. Some of the harmless pollutants are hydrogen, water vapor, oxygen and nitrogen. There are at least 200 different hydrocarbons that an internal combustion engine generates and emits at its exhaust. These include Methane (CH4), Acetylene (C2H2), Ethylene (C2H4), Ethane (C2H6), Propane (C3H6), Benzene (C6H6), Toluene (C7H8) etc., It also generates other organic compounds such as Aldehyde (CH3CHO), Ammonia (NH3), Hydrogen Sulfide (H2S), Formaldehyde (HCHO), Acetaldehyde (CH3CHO), Ethyl alcohol (C2H5OH), Methyl alcohol (CH3OH), Acetone (CH2COCH3), Formic acid (HCOOH), Nitric acid (HNO3) etc. These these compounds are rich sources of hydrogen. Internal combustion engine emits 1–2% of hydrogen showing that the engine is capable of hydrogen generation.
An internal combustion engine does not use any hydrogen or carbon. It only burns higher order fuels (hexane (C6H14), heptane (C7H16), octane (C8H18) etc.,), breaks them and converts them into lower order hydrocarbons. All the quantity of hydrogen present in the fuel before burning will be there in the exhaust of the engine. In addition to that more hydrogen will be added in the engine from the water vapor from air, since the engine uses air for burning. Moreover, efficiency of the internal combustion engine is only in the range of 24–30%. Thus, 70–76% of the energy from the fossil fuels is wasted and a large portion thereof—about 36%, comes out as un-burnt or partially burned fuel from the exhaust. There will be therefore plenty of hydrogen in the exhaust of the internal combustion engine. Therefore, it is possible to generate a large quantity of hydrogen using internal combustion engine. Exhaust gas of internal combustion engines can be used to generate hydrogen gas for fuel cells as well as for running another internal combustion engine using hydrogen rich gas as fuel.
There are many attempts reported to generate hydrogen by various techniques such as steam reforming, CO reforming, water gas shift reaction, biomass reforming, photo biological water splitting etc. However, no attempt has been made to generate hydrogen from the exhaust gas of an internal combustion engine.
U.S. Pat. No. 6,659,049 discloses generation of hydrogen using a Venturi device coupled with exhaust stream of an internal combustion engine which generates water. Using this water and an electrolyzer, hydrogen is generated and used in the internal combustion engine to reduce the emission of pollutants. The drawbacks are the method is useful for the reduction of pollutants emission but it does not make use of large quantity of hydrocarbons the engine emits and moreover it does not stop emission of all the pollutants. The hydrogen so generated will not be of any use for fuel cells.
U.S. Pat. No. 6,623,719 teaches a hydrogen generation system from hydrocarbons such as natural gas, propane, liquefied petroleum gas (LPG), alcohols, naphtha and other hydrocarbon fuels by using steam reforming technique. The drawbacks are the method uses valuable chemicals (fuels) that have many use and does not use the waste hydrocarbons generated in the internal combustion engine.
U.S. Pat. No. 6,506,510 relates to hydrogen generation using methane-cracking reaction. The drawbacks are it uses the raw methane gas for hydrogen production and does not use the waste hydrocarbons generated in the internal combustion engine.
U.S. Pat. No. 6,172,574 teaches generation of hydrogen by steam reforming of methanol and carbon monoxide. The drawbacks are it uses raw methanol for hydrogen production and does not use waste hydrocarbons generated in the internal combustion engine.
U.S. Pat. No. 4,104,191 teaches generation of hydrogen from flue gases by mixing it with fuel and converting in the presence of oxidant. The drawbacks are it requires fuel and it does not make use of waste hydrocarbon generated by the internal combustion engine.
There are no reports or patents, which use waste hydrocarbons or hydrogen rich compounds generated by internal combustion engines for generation of hydrogen for fuel cells or for running another internal combustion engine with hydrogen as the fuel. The compounds generated by the internal combustion engine, which are rich in hydrogen, can be used for the generation of hydrogen.